1. Field of the Invention
The present invention generally relates to the field of mobile communications, and more specifically relates to a cell information transmission method and user apparatus in mobile communications systems using Next generation mobile communications techniques.
2. Description of the Related Art
As a communications scheme to succeed W-CDMA, HSPDA, and HSUPA schemes, Long Term Evolution (LTE) is being studied in a standardization body called 3GPP. If the LTE radio access scheme becomes commonplace, it is anticipated that the LTE carriers/bands will be increased in order to increase system capacity. Then, depending on the operator, an existing UMTS carrier may be switched to an LTE carrier. For example, when first starting from a 5-MHz system to enhance to a 20-MHz system, it is possible to operate a single 20-MHz layer or to operate four 5-MHz layers in parallel.
Here, in a system having multiple carriers/bands, the load could be distributed unevenly on a certain carrier/band, so that radio resources could not be utilized effectively. This is mainly caused by too many carriers for which a user apparatus (UE) can stand by, difference in path loss among different bands/carriers, and coexistence of UEs of different capabilities. Particularly when carriers/bands are added in order to increase the system capacity, what is carrier/band ready and what is not coexist depending on the UE, causing a possible uneven distribution in the workload to specific carriers/bands. Such a situation brings about a problem that OAM control may become cumbersome for load balancing to smooth the uneven distribution of the workload.
In order to avoid such a problem, it is effective to use all layers (carriers/bands) to distribute a service while limiting a layer for which the user apparatus (UE) can standby. This is because limiting the number of layers which allows standing by for makes it possible to reduce the overhead of a paging channel (PCH) and a broadcast channel (BCH) and the burden of load balancing for standing by, so as to make it possible to simplify the OAM control as a result.
Limiting the number of layers allowing standing by for limits layers to be paged to only the layers allowing standing by for, making it unnecessary to transmit all system information sets in all layers. In order to implement the above, a configuration using two types of cells is being proposed (for example, see Non-patent document 1). In this proposal, two types of cells (i.e., a dominant cell, which allows the UE to stand by for, and a subordinate cell, which does not allow the UE to standby for) are set up. In the dominant cell, a synchronization channel (SCH), a full-broadcast channel (Full-BCH), a paging channel (PCH), and the other channels required for the UEs autonomous operation) are transmitted. On the other hand, in the subordinate cell, only the synchronization channel (SCH) and an information-limited broadcast channel (limited-BCH) are transmitted so as to reduce overhead.
Non-patent document 1: “Multi-band/carrier operation (1)-cell configuration”, Tdoc-R2-063391, 3GPP TSG RAN WG2 #56, 6-10 Nov. 2006, Riga, Latvia